Switch branch structure

1. A switch branch structure comprising: an input terminal, an output terminal, and a series stack of an N-number of transistors formed in an active device layer within a first plane, wherein a first one of the N-number of transistors is coupled to the input terminal, and an nth one of the N-number of transistors is coupled to the output terminal, where n is a positive integer greater than four; and a metal layer element having a planar body with a proximal end that is electrically coupled to the input terminal and a distal end that is electrically open, wherein the planar body is within a second plane spaced from and in parallel with the first plane such that the planar body overlaps more than at least two of the N-number of transistors to capacitively couple a radio frequency signal at the input terminal to between 50% and 80% of the N-number of transistors when the switch branch structure is in an off-state that blocks passage of the radio frequency signal from the input terminal to the output terminal.

2. The switch branch structure of claim 1 wherein the planar body of the metal layer element does not extend over between 25% and 50% of the N-number of transistors that are closest to the output terminal.

3. The switch branch structure of claim 1 wherein the planar body of the metal layer element extends over between 50% and 75% of the N-number of transistors that are closest to the input terminal.

4. The switch branch structure of claim 1 wherein the active device layer is rectangular with a layer length that extends between the input terminal and the output terminal and a layer width that is perpendicular to the layer length.

5. The switch branch structure of claim 4 wherein the planar body of the metal layer element is substantially rectangular with a body length that is between 50% and 75% of the layer length.

6. The switch branch structure of claim 4 wherein the planar body of the metal layer element is substantially rectangular with a body width that is between 50% and 100% of the layer width.

7. The switch branch structure of claim 4 wherein the planar body of the metal layer element is substantially rectangular with a body width that is between 50% and 100% of the layer width and a body length that is between 50% and 75% of the layer length.

8. The switch branch structure of claim 1 wherein the N-number of transistors are field-effect transistors that each has a gate, a source, and a drain.

9. The switch branch structure of claim 8 wherein the N-number of transistors are silicon-on-insulator type field-effect transistors.

10. The switch branch structure of claim 8 wherein drain-to-source voltages of each of the N-number of transistors range no more than 7% higher and 7% lower than exactly uniform drain-to-source voltages across each of the N-number of transistors when the radio frequency signal is applied at the input terminal with the switch branch structure in an off-state that blocks passage of the radio frequency signal from the input terminal to the output terminal.